Net Loss Per Share - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 28, 2025	Mar. 29, 2024
Numerator:
Net loss attributable to UCT	$ (5.0)	$ (9.4)
Denominator:
Basic weighted average common shares outstanding (in shares)	45.1	44.6
Diluted weighted average common shares outstanding (in shares)	45.1	44.6
Net loss per share attributable to UCT:
Basic (in dollars per share)	$ (0.11)	$ (0.21)
Diluted (in dollars per share)	$ (0.11)	$ (0.21)